Enable Missing Kernel Debugging Transport in Visual Studio 2012

By default, when you install Visual Studio 2012, you won't have Kernel Debugging in the list of transports as described in https://msdn.microsoft.com/en-us/library/windows/hardware/hh439359%28v=vs.85%29.aspx and in https://msdn.microsoft.com/en-us/library/windows/hardware/jj149675.aspx.  To fix this, install the WDK.